The modular substation systems installed in the fabrication yard were checked in 3 levels:
• Mechanical Completion,
• Pre-commissioning
• Commissioning
A check sheet is prepared as a result of these checks and test. These check sheets are used for future examination and reference also in the reassembly stage of the modules in the Final fabrication yard. If any component of substation is malfunctioning, it can be replaced at the during testing at the final fabrication stage and it not delay the delivery of the substation.
1. Mechanical Completion
Each and every components of substation are checked after installation. This procedure includes 10 to 15 checks of each component in a pre-prepared sequential order which is already approved and agreed by client. The Mechanical Completion testing includes the recording of the results, signing and stamping of the forms together with the inspectors of Client. Checking each component without interfering with the installation of other components in progress and without delaying the delivery of the substation is challenging. During initial installation, similar components like lamps, cable glands, MCT, cable trays, F&G sensors are checked and chances of problems during later installation work is very low.
2. Pre-Commissioning
Each simple components of the substation are checked during this stage. For example, for the lighting system each circuit was individually subjected to a function test;switching on/off, operating time of the batteries inside the lamps, checking the numbering of the components (TAG) belonging to the same circuit, measurement of the impedance for live-neutral and liveground malfunctions. Another pre-commissioning function check was done on the F&G sensors belonging to the same loop.
All the pre-commissioning activities were carried out in accordance with sequences stated in the relative forms. Pre-commissioning activities, including the recording of the results and affixing of stamps and signatures on the forms, were carried out together with the Client’s inspectors.
3. Commissioning
The function of each complete system sre checked in commissioning stage. Commissioning the HVAC system was very complex because it involved measuring the correspondence of the HVAC system to the design requirements. Therefore the temperatures at various points in the substation were measured and then the equipment involved was calibrated in order to obtain a thermal and air flow balance. Commissioning the HVAC also involved the power feed MCC of the HVAC, the variable speed drives for the fans, the static switches for the heaters, the F&G system and of course also the PLC of the HVAC.
Commissioning the lighting system was done by measuring the level of illumination in numerous zones and at predetermined points of the substations and recording the values measured for comparison with those required. An advantage of the modular substation system was the possibility of being able to add or move lamps easily in the modules to even out the level of illumination.
PROCEDURES AFTER TESTING
After successful checks and tests, the substation system are ready to transport to installation site. The following procedures are necessary for modular substations constructed in the Fabrication yard and not directly at the final installation site.
• Sea fastening
• Preservation
• Dismantling
• Load-out
1. Sea fastening
All the equipment installed in the modular substation was anchored mechanically to the module to prevent damage due to oscillations and vibrations during transport. The structure of the modules was also reinforced with temporary vertical and oblique braces to stiffen the structure for lifting and transport.
Modules with temporary braces
Equipment with large dimensions such as the transformers, panels and HVAC units were anchored using tape tie rods attached to the top part of the equipment and the floor of the module.
2. Preservation
All the equipments installed in the modular substation is then wrapped with sheets of special material, of a type that reduces humidity, to form a closed cover.
3. Dismantling
After separating the flanges of the air ducts and disconnecting the electrical cables, modules are mechanically separated and this need much manhours. Guiding pins are installed to ensure alignment of modules.
Guiding pin system
The parts of the modules that were without walls after separation were closed with temporary wood walls.
4. Loadout
Each module was loaded using cranes or special forklifts on the barge moored near the Fabrication yard and anchored for transport.
Transfer of module
REASSEMBLY
Reassembly in the final fabrication yard was performed following the detailed reassembly procedures agreed with the Client.
The sequence of activities is the same as in the fabrication yard but in reverse; for the substations with a number of modules in particular:
1. Unloading of the first module onto its final plinths
2. Removal of the temporary wall and ceiling
3. Removal of the temporary internal braces of the module
4. Unloading of the next module onto temporary plinths
5. Removal of temporary walls and ceiling
6. Positioning of the module above or next to the module already placed using the guiding pins
7. Removal of the temporary walls and temporary braces
8. Repeat from point 4 for the other modules
After mechanical reassembly of all the modules the air ducts are reassembled and the cables are reconnected following the Cable Schedule.
TESTING
After reassembly of the modules to form the complete substation, the procedures were followed for Mechanical Completion (only the components reassembled on site), Pre-commissioning and then Commissioning, based on the relative check sheets produced in the Fabrication yard.
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